Sheet feeding apparatus and image forming apparatus

ABSTRACT

A sheet feeding apparatus includes a sheet supporting unit which supports a plurality of sheets, a sheet feeding unit which feeds the sheet one by one from a stack of sheets supported by the sheet supporting unit, an air blowing unit which blows air to an end portion of the stack of sheets supported by the sheet supporting unit, the air blowing unit being able to change wind velocity of the blown air, a material setting unit which sets arbitrarily and registers the wind velocity of the air blown by the air blowing unit in accordance with a type of the sheet, and a sheet feeding control unit which controls the wind velocity of the air blown by the air blowing unit based on data registered by the material setting unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet feeding apparatus which separates and feeds a sheet one by one from a stack of sheets stacked in a sheet storage portion.

2. Related Background Art

In an image forming apparatus such as a copying machine and a printer, continuously feedable cut sheet has been generally limited to high-quality paper or standard paper specified by a copy machine manufacturer. In such paper, evenness of its surface is low and air permeability is also low, so that air easily flows into between the sheets. When the sheet is drawn one by one from the stacked sheets, there is a low possibility that the sheets are attracted on each other to generate double feeding.

Recently, as recording medium becomes diversified, demand of the image formation is increased even for the sheet having the even surface such as art paper and coated paper in addition to thick paper, an OHP sheet, tracing paper, and the like. In the art paper and coated paper, coating treatment is applied to the surface of the sheet in order to enhance gloss and whiteness from marketing needs of colorization. However, since the OHP sheet, the tracing paper, the art paper, and the coated paper have the higher evenness and air permeability, particularly when the sheets are stacked under environment of high humidity, the sheets are attracted on each other. Therefore, in the friction separation method generally used in the conventional copying machine and printer, there has been generated a problem that the double feeding or miss feed often occurs.

On the other hand, an air sheet supply method, in which the sheet is raveled-out by blowing air from a side surface of the stack of sheets and the sheet is simultaneously separated and fed one by one from the upper most sheet with a suction apparatus and a conveying belt which are arranged above the stack of sheets, is adopted in a few of copying machines and in a printing industry. When compared with the friction separation method, the air sheet supply method has the following merits. That is, 1) setting latitude of a sheet supply condition is broad for a material (type of sheet), 2) the air sheet feeding method is adaptable to high-speed sheet feeding, 3) high durability, and 4) low running cost.

There have been made many proposals concerning the air sheet supply method. The proposal disclosed in Japanese Patent Application Laid-Open No. S62-249835 can be cited as an example. As shown in FIG. 17, Japanese Patent Application Laid-Open No. S62-249835 proposes the method in which, in a sheet feeding apparatus 1, the air is blown with an air blower device 7 from a direction parallel to the upper surface of the sheet to the side surface at a front end of sheets S stacked on a sheet supply stage 3, and negative pressure is generated in a suction pipe 11 opened at an upper side of the sheet by a negative pressure generation device 9 to suck the sheet. The sheet feeding apparatus 1 is intended to surely separate the uppermost sheet from the next sheet, such that the uppermost sheet is floated from the sheets S stacked on the sheet supply stage 3 by the sucking operation from the opening to blow the air from the air blower device 7 into a gap formed between the uppermost sheet and the next sheet.

As shown in FIG. 18, Japanese Patent Application Laid-Open No. H11-005643 discloses a sheet feeding apparatus 21 including a sheet supply tray 23 stacking the sheets S, sheet supplying means (not shown) for feeding the sheet from the sheet supply tray 23, air blowing means 27 for blowing the air from the direction perpendicular to the side surface of the sheets to the side surface and upper surface of the stacked sheets, and flow path moving means 30 for moving a flow path of the air blown from the air blowing means 27 in the direction perpendicular to the sheet surface.

The flow path moving means 30 includes a guide rail (not shown) which supports the air blowing means 27 while being able to move the air blowing means 27 in the perpendicular direction, an electric motor 32, and a cam plate 34 which is fixed to an output shaft of the electric motor 32 and moves the air blowing means 27 while sliding on a lower surface of the air blowing means 27. When the cam plate 34 is rotated by rotating the electric motor 32, the whole of air blowing means 27 is moved in the perpendicular direction. In the sheet feeding apparatus 21, an opening portion (air blowing outlet) of the air blowing means 27 always has a constant opening area, so that the air is moved in the direction perpendicular to the sheet surface relative to the side surface of the sheets S by moving the whole of air blowing means 27 in the perpendicular direction.

According to the sheet feeding apparatus 21, the flow path can be moved in the perpendicular direction. Further, however, the opening portion of the air blowing means 27 always has the constant opening area in moving the flow path in the perpendicular direction, the side surface of the sheets S is arranged to be opposite to the opening portion, which results in formation of an air narrowing-down portion which reduces the area of the opening portion to narrow down the air flow blown from the opening portion. As a result, the sheet feeding apparatus 21 can sequentially float the sheet from the uppermost sheet of the stacked sheets S to release the close contact between sheets in all the stacked sheets S.

However, as described above, since the OHP sheet, the tracing paper, the art paper, and the coated paper have the higher evenness and air permeability, the attraction between the sheets is generated particularly when the sheets are stacked under the environment of the high humidity. In the case of the sheet feeding apparatus 1 adopting the conventional air sheet supply method, because the air blown to the side surface of the stack of sheets is the constant flow, the upper portion of the stack of sheets is floated in the shape of the stack at an interface in which attraction force is relatively weak. As a result, the air cannot flow into the gap of the floated stack of sheets, and it is very difficult to surely separate the sheets one by one.

In the sheet feeding apparatus 21 which is of another conventional example including the flow path moving means, although effect of releasing the attraction between the sheets is obtained for the relatively thin sheets, the close contact between the sheets is not released for the relatively thick sheets due to a heavy weight and a strong body. Therefore, the sheet feeding apparatus 21 cannot solve the miss feed and the double feeding.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the invention to provide the sheet feeding apparatus which realizes the adaptation to various materials from the thick paper to the thin paper by user setting and releases surely the attraction between the sheets with a simple configuration to prevent the generation of the miss feed or the double feeding, thereby reliability of the sheet feeding apparatus is intended to be improved.

The invention is a sheet feeding apparatus including sheet supporting means for supporting a plurality of sheets, sheet feeding means for feeding the sheet one by one from a stack of sheets supported by the sheet supporting means, air blowing means for blowing air to an end portion of the stack of sheets supported by the sheet supporting means, the air blowing means being able to change wind velocity of the blown air, material setting means for setting arbitrarily and registering the wind velocity of the air blown by the air blowing means in accordance with a type of the sheet, and sheet feeding control means for controlling the wind velocity of the air blown by the air blowing means based on data registered by the material setting means.

The invention is a sheet feeding apparatus including a paper deck which supports a plurality of sheets, a suction belt which is arranged above the paper deck, the paper deck sucking and feeding the uppermost sheet, an air blowing duct which is provided in front of a stack of sheets supported by the paper deck, a blowing fan which supplies air to the air blowing duct, material setting means for setting arbitrarily and registering the wind velocity of the air blown by the air blowing means in accordance with a type of the sheet, and sheet feeding control means for controlling the wind velocity of the air blown by the air blowing means based on data registered by the material setting means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view explaining a first embodiment of the invention;

FIGS. 2A, 2B, 2C, and 2D are sectional views showing swing operation in the first embodiment;

FIGS. 3A, 3B, 3C, and 3D are explanatory views of an attraction mechanism of coated paper;

FIGS. 4A and 4B are explanatory views of attraction characteristics of the coated paper;

FIG. 5 is an explanatory view of the swing operation for thin paper;

FIGS. 6A and 6B are sectional views explaining the swing operation for thick paper in the first embodiment;

FIGS. 7A and 7B are explanatory views of effectiveness of swing stop for the thick paper;

FIG. 8 is an explanatory view of a sheet supply separable area for each type of the coated papers;

FIG. 9 is a flow chart showing setting registration of a user material;

FIG. 10 is a view showing a screen of user material registration;

FIG. 11 is a flow chart showing user material fine adjustment setting registration;

FIG. 12 is a view showing the screen of material fine adjustment registration;

FIG. 13 is a view showing an example of a material storage table;

FIG. 14 is a flow chart showing determination of air sheet feeding conditions;

FIGS. 15A and 15B are sectional views explaining the swing operation for the thin paper in a second embodiment;

FIG. 16 is a sectional view explaining the swing stop for the thick paper in the second embodiment;

FIG. 17 is a sectional view showing an example of the conventional air sheet feeding apparatus; and

FIG. 18 is a sectional view showing an example of the conventional air sheet feeding apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to accompanying drawings, preferred embodiments of the invention will be described below.

(Overall Configuration)

FIG. 1 is a sectional view showing a configuration of a main part of a copying machine according to a first embodiment of the invention.

The copying machine includes an image reader 200 which reads an original image, a printer 300, and a sheet supply portion 400. The sheet supply portion 400 includes paper decks 401 and 451 which commonly have a sheet supply mechanism. The paper deck 401 can store 1,000 sheets and the paper deck 451 can store 1500 sheets. The sheet supply portion 400 will be described in detail later.

An original feeding apparatus 100 is mounted on the image reader 200. The original feeding apparatus 100 sequentially feeds original D set upward on an original tray 101 from a front end page one by one toward the left, passes the original D through a flow read position on an original plate (or a platen glass) 102 from the left toward the right via a curved path, and then discharges the original D toward an outside paper discharge tray 112.

When the original D passes through the flow read position on the original glass 102 from the left toward the right, the original image is read with scanner means 104 held at a position corresponding to the flow read position. This reading method is one which is generally referred to as an original flow read. Specifically, when the original D passes through the flow read position, a read surface of the original D is irradiated with light of a lamp 103 of the scanner means 104, and the light reflected from the original D is introduced to a lens 108 through mirrors 105, 106, and 107. The light which has passed through the lens 108 is focused on an image surface of an image sensor 109.

Original read scan is performed by conveying the original D so that the original D passes through the flow read point from the left toward the right. In the original read scan, the direction orthogonal to a conveying direction of the original D is set to a main scanning direction, and the conveying direction is set to a sub-scanning direction. That is, in passing the original D through the flow read point, the whole of original image is read such that the original D is conveyed in the sub-scanning direction while the original image is read one line by one line in the main scanning direction with the image sensor 109, and the image which has been optically read is converted into image data with the image sensor 109 and output from the image sensor 109. After predetermined processing is performed to the image data output from the image sensor 109 in the later-mentioned image signal control portion 202, the image data is output as a Video signal to an exposure control portion 110 of the printer 300.

It is also possible that the original D is conveyed onto the original glass 102 with the original feeding apparatus 100 to be stopped at a position and the original D is read by scanning the scanner means 104 from the left to the right. This read method is one referred to as so-called fixed original read.

When the original D is read without using the original feeding apparatus 100, a user raises the original feeding apparatus 100 to put the original D on the original glass 102, and then the original D is read by scanning the scanner means 104 from the left to the right. That is, when the original is read without using the original feeding apparatus 100, the fixed original read is performed.

The exposure control portion 110 of the printer 300 modulates and outputs a laser beam based on the input video signal. A photosensitive drum 111 is irradiated with the laser beam while the laser beam is scanned by a polygon mirror. An electrostatic latent image is formed on the photosensitive drum 111 in accordance with the scanned laser beam. At this point, in the fixed original read, the exposure control portion 110 outputs the laser beam so that the correct image (not mirror image) is formed.

The electrostatic latent image on the photosensitive drum 111 is visualized as a developer image by a developer supplied from a developing device (not shown). The sheet is supplied from the paper decks 401 and 451 of the sheet supply portion 400 at timing synchronized with the start of the irradiation of the laser beam. Then, the sheet is conveyed to between the photosensitive drum 111 and a transfer portion 116 through a resist roller 115. The developer image formed on the photosensitive drum 111 is transferred onto the sheet supplied by the transfer portion 116.

The sheet on which the developer image has been transferred is conveyed to a fixing portion 117. The fixing portion 117 fixes the developer image on the sheet by heating the sheet under pressure. The sheet which has passed through the fixing portion 117 is discharged to a first discharge tray 119 through a first discharge roller 118 or to a second discharge tray 121 through a second discharge roller 120 by changing a flapper (not shown).

(First Embodiment)

Then, the paper deck of the air sheet supply method according to the invention will be described in detail.

The paper deck 401 of the air sheet supply method in a first embodiment stacks and stores the stack of sheets on an intermediate plate 403 included in a sheet storage 402. Rails 404 and 405 are provided on both sides at a lower end portion of the sheet storage 402, and the sheet storage 402 can be drawn from a front side of the apparatus main body (direction perpendicular to the paper surface). The stack of sheets stacked and stored in the sheet storage 402 is fixedly placed at a position by a pre-separation plate 406 at a front end portion of the stack of sheets, a rear end regulation plate (not shown) at a rear end portion, and a side regulation plate (not shown) at a side portion.

An environmental measurement sensor 460 as environmental measurement means for measuring the environment such as temperature and humidity inside the sheet supply portion is arranged in the sheet supply portion 400. Further, a control portion C as the later-mentioned sheet feeding control means for control the separation and feed of the sheet is also arranged in the sheet supply portion 400.

FIGS. 2A to 2D is a schematic sectional view of the main part of the sheet supply portion 400. The sheet supply portion 400 includes a suction duct 408 above the stack of sheets stacked on the intermediate plate 403. The suction duct 408 is connected to a suction fan F1 to be able to generate suction static pressure above the stack of sheets. A suction belt 407, which has a multiplicity of holes so that the holes surround the suction duct 408, is arranged while being able to be rotated in the sheet supply direction (arrow direction in FIG. 2D).

A blowing fan F2 and a blowing duct 413 as air blowing means of the invention are provided on the front side in the sheet feeding direction of the paper deck 401. The blowing duct 413 is connected to the blowing fan F2 and provided with an opening 414 opened toward the side surface at the front end of the stack of sheets stacked and stored in the sheet storage 402. The blowing fan F2 supplies the air to the blowing duct 413. A heater 422 is arranged between the blowing fan F2 and the blowing duct 413. The heater 422 heats the blowing air to improve raveling-out properties of the sheet. For the temperature of the blowing air, the optimum temperature according to the material has been found by experiments and the like. The temperature of the blowing air can be adjusted by controlling the heater 422.

The sheet supply portion 400 also includes a shutter 415 which can be moved in the substantially vertical direction between the side surface of the stack of sheets and the opening 414. A part of the shutter 415 includes a slit 416 whose width is sufficiently smaller than that of the opening 414. Detection means 417 for detecting a phase of the moving shutter 415 is provided in the sheet supply portion 400. Alternatively, it is also possible to use the plurality of fans to perform ON/OFF control without providing the shutter mechanism. The sheets in the upper portion of the stack of sheets are raveled-out by the air blown from the opening 414.

A separation air blowing nozzle 420 for blowing the air along the lower surface of the suction belt 407 is arranged in the upper portion of the blowing duct 413.

In sheet separating and feeding operation, as shown in FIGS. 2A to 2D, the raveling-out, the floatation, and the separation of the sheet are performed by blowing the air from the side end of the stack of sheets while the shutter 415 is vertically moved, and the sheets except for the uppermost sheet are surely separated from one another. The uppermost sheet is sucked to the suction belt 407 by the air from the separation air blowing nozzle 420.

Then, the attraction mechanism will be clarified for the coated paper, in which the attraction phenomenon is generated under high humidity and the problems such as the miss feed and the double feeding can not be avoided in the conventional sheet supply method.

As shown in FIG. 3A, when the stack of sheets of the coated paper is exposed under the high-humidity environment, the surface of the uppermost sheet and the end portions of the stacked sheets absorb moisture. Then, as shown in FIG. 3B, the uppermost sheet is expanded and peripheries of the sheets subsequent the uppermost sheet are swelled. At this point, because the expansion is smaller in a backside of the uppermost sheet, a convex deformation phenomenon is generated as shown in FIG. 3C. Because the coated paper has the high evenness and the low air permeability, the air flow into between the sheets is not substantially generated. Therefore, as shown in FIG. 3C, when the uppermost sheet of the coated paper is expanded to generate the convex deformation, there is generated the phenomenon (attraction by moisture-absorption of the uppermost sheet), in which a volume between the sheets is expanded and the negative pressure is generated to cause the attraction. The moisture absorption proceeds from the peripheries and the peripheries are swelled in the stack of sheets except for the uppermost sheet.

Since an area near the central portion is not swelled, there is generated the phenomenon (attraction by moisture-absorption of the paper peripheries), in which volume expansion occurs in the direction of a sheet thickness and the negative pressure is generated to cause the attraction. As shown in FIG. 3D, sometimes the convex deformation is also generated in the second sheet by affection of the convex deformation of the uppermost sheet and the negative pressure is generated between the second sheet and the third sheet to cause the attraction. Sometimes this phenomenon extends from the third sheet to tens of sheets. The phenomenon is referred to as chain deformation. As described above, the mechanism of the coated paper attraction under the high humidity includes three types of the attraction phenomena. The three types of the attraction phenomena have the characteristics shown in FIGS. 4A and 4B.

As shown in FIG. 4A, since the negative pressure by the convex deformation of the uppermost sheet is generated by absorbing the moisture from the overall surface of the sheet, a scale of the negative pressure by the convex deformation becomes much larger than that of the negative pressure by the swelling of the peripheries of the sheet. That is, moisture-absorption and attraction force of the uppermost sheet is much larger than moisture-absorption and attraction force of the paper peripheries. As shown in FIG. 4B, in relatively thin OK coated paper L; 72 g/m², the chain deformation is easy to generate due to weak paper body, and the chain deformation is generated up to about 40 sheets. On the contrary, in relatively thick double-side coated card paper; 317 g/m², it is found that the convex deformation by the negative pressure of the paper hardly overcomes against the paper body and the chain deformation attraction is not substantially generated.

Therefore, in the sheet feeding apparatus which is disclosed in Japanese Patent Application Laid-Open No. 11-005643 and includes the conventional flow path moving means, the sheet feeding apparatus only has constant moving means irrespective of difference in the attraction phenomena by the above-described material (type of sheet), so that the sheet feeding apparatus is not sufficient for the release of the close contact between the sheets and the sheet feeding apparatus can not solve the miss feed and the double feeding.

The operation of the invention, which is based on the clarified attraction mechanism of the coated paper, will be described in detail below. At first the case of the thin paper supply will be described. As shown in FIGS. 2A to 2D, when the thin coated paper (for example, OK royal coated paper; 64 g/m²) is set on the paper deck 401 to insert the paper into the main body, the intermediate plate 403 is lifted by a lift-up motor (not shown) to be positioned at a predetermined height with sheet height detection means (not shown). Then, the sheet supply operation is started by pressing a copy button.

While the suction fan F1 above the stack of sheets starts the sucking operation, the blowing fan F2 is operated to blow the air to the side surface of the stack of sheets. At this point, as shown in FIGS. 2A to 2D, the shutter 415 is vertically reciprocated (hereinafter, referred to as swing operation) between the side surface of the stack of sheets and the opening 414 of the blowing duct 413 by transferring drive from a drive source (not shown). Since the slit 416 whose width is sufficiently narrower than that of the opening 414 is formed in the shutter 415, when the slit 416 reaches the opening 414, the wind velocity of the air passing through the slit 416 is increased because of the difference in the widths and the strong air can be blown.

When the swing operation of the shutter 415 is performed, the air which has passed through the slit 416 to have the increased wind velocity is blown to the side surface of the stack of sheets while continuously moving upward, so that it is expected that the sheet feeding apparatus of the invention has the better raveling-out effect when compared with the conventional steady air flow. As shown in FIGS. 2A to 2D, FIGS. 3A to 3D, FIGS. 4A to 4B, and FIG. 5, in the thin coated paper, the attraction can be effectively released by performing the swing operation for the uppermost sheet having the strong attraction force and tens of sheets in the upper portion of the stacked sheets in which the chain deformation attraction is generated. Therefore, the better separating and feeding operation can be surely performed one sheet by one sheet from the uppermost sheet by rotating the suction belt 407.

In the case of the feeding of the sheet such as the art paper and the coated paper in which the attraction phenomenon is easily occurs under the high humidity, it is also possible that plural-time vertical swing operations of the shutter 415 are performed as pre-operation of the sheet feeding.

Then, the feeding operation of the thick coated paper will be described. As shown in FIG. 6A, in the case of the sheet feeding of the thick paper (for example, double-side coated card paper; 317 g/m²), the slit 416 of the shutter 415 is fixed at a position including a sheet-supply sheet-surface height, i.e., the swing operation is stopped. The positional detection can be performed by the detection means 417 and a flag portion 418 formed in the shutter 415.

Sometimes the separation effect is also lost when the swing operation is performed in the thick coated paper. As shown in FIG. 7A, when the swing operation is performed in the thick coated paper, the little chain deformation attraction is generated without releasing the attraction of the uppermost sheet in which the strong attraction is generated, so that the separation and floatation are generated in the attraction portion in the peripheries of the paper where the attraction is weak. Further, there is also a demerit that decreases the time when the strong air is blown to between the uppermost sheet and the subsequent sheet where the strongest attraction is generated. Therefore, as shown in FIGS. 6B and 7B, it is effective that the swing operation is stopped and the strong air is continuously blown to between the uppermost sheet and the subsequent sheet, where the attraction is strong, with pinpoint accuracy.

Based on the above-described attraction mechanism of the coated paper, the chain deformation attraction can be released by the swing operation for the thin coated paper, and the moisture-absorption and attraction of the uppermost sheet can be released by stopping the swing operation for the thick coated paper. FIG. 8 shows sheet supply separable area maps for various sheets of the coated paper as experimental results. The experimental results in FIG. 8 show that the swing operation is preferable only to the sheet not more than 105 g/m² and the swing stop is preferable to the sheet more than 105 g/m². Material setting means in which the optimum separating and feeding conditions are set and registered in accordance with the material (type of sheet) by the user will be described referring to a flow chart shown in FIG. 9 and an operation screen shown in FIG. 10.

The suction force of the suction belt 407 by the suction duct 408 can be adjusted by controlling the number of revolutions of the suction fan F1 to change the amount of suction. The wind velocity of the raveling-out air (the mount of raveling-out air) passing through the opening 414 of the blowing duct 413 can be adjusted by controlling the number of revolutions of the blowing fan F2. At this point, the amount of air suction of the suction fan F1 for generating the suction force in the suction belt 407 is referred to as the amount of separation air, and the amount of air blow which is blown from the opening 414 of the blowing duct 413 is referred to as the amount of raveling-out air.

In the user material registration (Step 1301) of the registration flow shown in FIG. 9, the user sets and registers a name of the material, and the amount of separation air, the amount of raveling-out air, the air temperature, and ON/OFF of the swing operation in accordance with the material on the operation screen shown in FIG. 10. When a registration button is pressed after the setting, the name of the material, the amount of separation air, the amount of raveling-out air, the air temperature, and ON/OFF of the swing operation are stored in a storage table shown in FIG. 13 (Step 1302). In this case, although the name of the material, the amount of separation air, the amount of raveling-out air, the air temperature, and ON/OFF of the swing operation can be cited as examples of setting items, the number of fans used and the like may be added as the setting item.

In the storage table of FIG. 13, initial values of the amount of separation air, the amount of raveling-out air, the air temperature, ON/OFF of the swing operation, the blowing air temperature, and the number of blowing fans F2 (in the case of the plurality of fans) in accordance with the material are stored in each material (data described by “Material-” in FIG. 13). Numeric characters in FIG. 13 indicate the level of the amount of air. The numeric character is one in which the difference between the maximum value and the minimum value is divided into ten equal parts, assuming that each of the maximum values of the amount of separation air and the amount of raveling-out air is set to. 10 and each of the minimum values of the amount of separation air and the amount of raveling-out air is set to 0.

In the registration using the material setting means, the data changed by each user relative to the initial value can be registered, and the new data for the material in which the initial value is not set can be also registered.

In order that the user can perform the further fine adjustment, user fine adjustment setting means is also included. The user fine adjustment setting means sets and registers the fine adjustment of the setting items such as the amount of separation air, the amount of raveling-out air, the air temperature, and ON/OFF of the swing operation. The user fine adjustment setting means will be described below referring to the flow chart shown in FIG. 11 and a user fine adjustment registration screen shown in FIG. 12.

In the flow chart of FIG. 11, the input of the operation screen shown in FIG. 12 is performed in Step 1401. In this case, the name of the material stored in the storage table of the name is called to perform the fine adjustment of the amount of separation air, the amount of raveling-out air, the air temperature, and ON/OFF of the swing operation. With reference to a size, it is set whether the size is considered or not. When the user presses the registration button, the flow proceeds to Step 1402 to store the setting items of the fine adjustment in a user fine adjustment storage table (not shown) as user fine adjustment storage means.

The flow to the step in which the actual air sheet supply conditions are determined will be described referring to FIG. 14.

In step 1801, it is detected which paper decks 401 or 451 is selected. In Step 1802, the material set in the paper deck is detected (the user can set the material). In Step 1803, it is searched whether the material detected in Step 1802 is registered in the storage table in the flow of FIG. 9 or not. When the material is registered in the storage table, the flow proceeds to Step 1805. When the material is not registered in the storage table, the flow proceeds to Step 1804.

In Step 1804, the initial values are read. As shown in FIG. 13, the initial values is drawn from the material storage table in which the amount of separation air, the amount of raveling-out air, the air temperature, ON/OFF of the swing operation, the blowing air temperature, and the number of fans (in the case of the plurality of fans) the material are stored in each material. In the case where the material storage table is not included, it is also possible to prompt the user to set the initial values on the operation screen shown in FIG. 10. Then, the flow proceeds to Step 1808.

In Step 1805, the air sheet supply conditions concerning the registered material are read out from the storage table, and the flow proceeds to Step 1806. In Step 1806, it is searched whether the fine adjustment is set by the user or not. When the fine adjustment is registered, the flow proceeds to Step 1807. When the fine adjustment is not registered, the flow proceeds to Step 1808. In Step 1807, the adjustment values are read out from the fine adjustment item table for the selected material, and the flow proceeds to Step 1808. In Step 1808, it is searched whether the environment is considered or not in the air sheet supply condition. When the environment is set, the flow proceeds to Step 1810. When the environment is not set, the flow proceeds to Step 1809. In Step 1809, the initial values of the environment setting are read out, and the flow is ended. In the initial values of the environment setting, the material storage table in which each value is set in each material as shown in FIG. 13 can be read out from the storage table (not shown) previously set.

In Step 1810, the current environments are measured with the environmental measurement sensor 460, the conditions suitable to the environments are read out, and the flow is ended.

It is also possible that each table such as the material storage table shown in FIG. 13 is obtained through a network. When the registration can be performed through the network as well as the initial conditions, it becomes effective means in the case where the new material appears on the market.

While the high-accuracy control is performed by considering the environmental conditions with the environmental measurement sensor 460 in the flow chart of FIG. 14, it is also possible to perform the control of the invention without considering the environmental conditions by eliminating Steps 1808, 1809, and 1810.

(Second Embodiment)

A second embodiment will be described referring to FIGS. 15 and 16. The same component of the second embodiment as that of the first embodiment is indicated by the same reference numeral, and the description of the same component will not be repeated here. Only the portion different from the first embodiment is described, and the configuration which is not described is same as the first embodiment.

The second embodiment includes a swing nozzle 421 as changing means of the invention for changing the wind direction in the blowing duct 413 provided on the front side of the stack of sheets. The swing nozzle 421 can vertically rotate the side end portion in the upper portion of the stack of sheets.

In the case of the thin coated paper, similarly to the first embodiment, the swing nozzle 421 performs the blowing operation to the sheet lifted up to the position of the sheet-supply sheet-surface height while continuously moving the air having the higher wind velocity. As shown in FIGS. 15A and 15B, the swing nozzle 421 blows the air to the side surface of the stack of sheets while repeating the swing operations of (a) substantially horizontal direction and (b) obliquely downward direction.

Therefore, it is very effective to release the attraction of the thin coated paper in which the chain deformation attraction is generated. The air whose wind direction is continuously changed can be given, so that there is the merit that the separation effect is extremely increased by blowing the air into the gap between the sheets attracted to each other or the gap between the sheets stacked on each other with the sheets slightly shifted from each other. The number of reciprocating operations and moving aped of the swing nozzle 421 are registered so as to be arbitrarily set by the material of the sheet, the size of the sheet, and the environmental conditions, and the finer adjustment can be performed by using the fine adjustment storage table in which the fine adjustment can be performed in each material.

In the case of the thick coated paper, as shown in FIG. 16, the swing nozzle 421 is fixed to the position in the substantially horizontal direction to stop the swing operation, and then the swing nozzle 421 blows the air to the upper portion of the stack of sheets. This allows the strong air to be blown for the sufficient time in order to release the moisture-absorption and attraction of the uppermost sheet in which the attraction force is the maximum.

As described above, even in the embodiment, the swing nozzle 421 having the high raveling-out effect is operated in order to release the chain deformation attraction in the case of the thin coated paper, and the swing is stopped to release the attraction of the uppermost sheet in the case of the thick coated paper. As a result, the attraction of any coated paper can be released by the secure inflow of the air between the sheets.

In the first and second embodiments described above, the air blow in the sheet supply operation or the presence or absence of the swing operation can be arbitrarily set by the conditions such as the material. In order to improve the raveling-out effect, it is possible to perform the air blow for the predetermined amount of time before a job or the swing operation. In each embodiment, the sheet supply method may be any one of a retard roll method, separation pawl method, a vacuum feed method, and the like. The air blowing means may adopt either an axial flow method or a sirocco method or use a compressor device. The air blow direction may be any one of the side surfaces of the front, rear, left, and right sides of the stack of sheets.

This application claims priority from Japanese Patent Application No. 2003-207885 filed on Aug. 19, 2003, which is hereby incorporated by reference herein. 

1. A sheet feeding apparatus comprising: sheet supporting means for supporting a plurality of sheets; sheet feeding means for feeding the sheet one by one from a stack of sheets supported by said sheet supporting means; air blowing means for blowing air to an end portion of the stack of sheets supported by said sheet supporting means, said air blowing means being able to change wind velocity of the blown air; material setting means for setting arbitrarily and registering the wind velocity of the air blown by said air blowing means in accordance with a type of the sheet; and sheet feeding control means for controlling the wind velocity of the air blown by said air blowing means based on data registered by said material setting means.
 2. A sheet feeding apparatus comprising: sheet supporting means for supporting a plurality of sheets; sheet feeding means for feeding the sheet one by one from a stack of sheets supported by said sheet supporting means; air blowing means for blowing air to a side surface of the stack of sheets supported by said sheet supporting means, said air blowing means being able to change wind velocity of the blown air; material setting means for setting arbitrarily and registering the wind direction of the air blown by said air blowing means in accordance with a type of the sheet; and sheet feeding control means for controlling the wind direction of the air blown by said air blowing means based on data registered by said material setting means.
 3. A sheet feeding apparatus according to claim 1, further comprising material fine adjustment setting means for setting and registering fine adjustment of the wind velocity of the air in accordance with the type of the sheet, and said sheet feeding control means controls the wind velocity of the air blown by said air blowing means based on a setting value registered by said sheet feeding control and said material fine adjustment setting means.
 4. A sheet feeding apparatus according to claim 2, wherein said air blowing means is configured to be able to swing in a vertical direction, and said material setting means sets and registers ON/OFF of a swing of said air blowing means and changes a wind direction of the air by performing ON/OFF of the swing of said air blowing means based on the setting by said material setting means.
 5. A sheet feeding apparatus according to claims 1 or 2, further comprising environmental measurement means for measuring environment near said sheet supporting means, and said sheet feeding control means performs control based on the setting of said material setting means and measurement result of said environmental measurement means.
 6. A sheet feeding apparatus according to claims 1 or 2, wherein said material setting means comprises a material storage table in which initial data is stored in each material, said material setting means controlling the air blowing of said air blowing means based on the initial data of the material storage table when the registration is not performed by said material setting means.
 7. A sheet feeding apparatus according to claims 1 or 2, wherein said material setting means comprises a material storage table which stores data registered in each material, the initial data suitable to each material is stored in the material storage table, and said material setting means controls the air blowing of said air blowing means based on the initial data of the material storage table when the registration is not performed by said material setting means.
 8. A sheet feeding apparatus according to claims 1 or 2, wherein said sheet feeding means comprises suction belt which sucks the uppermost sheet of the sheets supported by said sheet supporting means, said material setting means can set arbitrarily and register strength of suction force of the suction belt, and said sheet feeding control means controls the suction force based on the data registered by said material setting means.
 9. A sheet feeding apparatus comprising: a paper deck which supports a plurality of sheets; a suction belt which is arranged above said paper deck, said paper deck sucking and feeding the uppermost sheet; an air blowing duct which is provided in front of a stack of sheets supported by said paper deck; a blowing fan which supplies air to said air blowing duct; material setting means for setting arbitrarily and registering the wind velocity of the air blown by said air blowing means in accordance with a type of the sheet; and sheet feeding control means for controlling the wind velocity of the air blown by said air blowing means based on data registered by said material setting means.
 10. A sheet feeding apparatus according to claim 9, wherein said air blowing duct comprises a shutter which can swing in a vertical direction, and said material setting means sets and registers ON/OFF of a swing of the shutter and changes a wind direction of the air by performing ON/OFF of the swing of the shutter based on the setting by said material setting means.
 11. A sheet feeding apparatus according to claim 9, wherein said air blowing duct comprises a swing nozzle which can swing in the vertical direction, and said material setting means sets and registers ON/OFF of the swing of the swing nozzle and changes the wind direction of the air by performing ON/OFF of the swing of the swing nozzle based on the setting by said material setting means.
 12. A sheet feeding apparatus comprising: a sheet feeding apparatus according to any one of claims 1 to 11; and an image forming portion which forms an image fed by the sheet feeding apparatus. 